Which of the following instruments is specifically known for detecting exoplanets?

The instrument specifically known for detecting exoplanets is the Kepler space telescope. Launched in 2009, Kepler was designed to survey a portion of the Milky Way galaxy to discover Earth-sized and smaller planets orbiting other stars. It utilized a technique called the transit method, where the telescope monitored the brightness of stars over time to identify periodic dips in brightness that indicate a planet passing in front of its star.

This method allowed Kepler to detect thousands of exoplanets and significantly advanced our understanding of the variety of planetary systems possible in our galaxy. Its focused mission and the specificity of its design for identifying exoplanets are what set Kepler apart from other instruments.

In contrast, while the other instruments mentioned have important roles in astronomical observations, they are not specifically tailored to the detection of exoplanets. SOFIA, the Hubble Space Telescope, and Chandra primarily serve different purposes, such as studying celestial phenomena and imaging, rather than the dedicated search for exoplanets that defines Kepler's mission.